There is a phenomenon that is rarely commented on but which is as common as it is significant.

For at least two generations, countless conservative parents have seen their adult children reject their core values.

I have met these parents throughout America. I have spoken with them in person and on my radio show. Many have confided to me — usually with a resigned sadness — that one or more of their children has adopted left-wing social, moral and political beliefs.

A particularly dramatic recent example was a pastor who told me that he has three sons, all of whom have earned doctorates — from Stanford, Oxford and Fordham. What parent wouldn’t be proud of such achievements by his or her children?

But the tone of his voice suggested more irony than pride. They are all leftists, he added wistfully.

“How do you get along?” I asked.

“We still talk,” he responded.

Needless to say, I was glad to hear that. But as the father of two sons, I readily admit that if they became leftists, while I would, of course, always love them, I would be deeply saddened. Parents, on the left or the right, religious or secular, want to pass on their core values to their children.

As a father, my purpose is not to pass on my seed, but to pass on my values. Just about anyone can biologically produce a child. That ability we share with the animals. What renders us distinct from animals is that we can pass on values. As the Latin puts it, animals only have “genitors;” humans have “paters.” Or as the Hebrew has it, parent (horeh) comes from the same root as teacher (moreh). That is why Judaism puts teachers (of religious/moral values) on the same plane as parents.

So it is sad when a parent who believes, for example, in the American trinity of liberty, “In God We Trust” and “E Pluribus Unum” has a child who believes that equality trumps liberty, that a secular America is preferable to a God-centered one, and that multiculturalism should replace the unifying American identity.

It is sad when a pastor, or any other parent, who believes that the only gender-based definition of marriage that has ever existed — husband and wife — has a child who regards the parent as a bigot for holding on to that definition.

It is sad when a parent who believes that America has always been, in Lincoln’s famous words, “the last best hope of earth,” has a child who believes that America has always been little more than an imperialist, racist and xenophobic nation.

That this happens so often raises the obvious question: Why?

There are two reasons.

One is that most parents with traditional American and Judeo-Christian values have not thought it necessary to articulate these values to their children on a regular basis. They assumed that there was no need to because that was true for much of American history, when the society at large held those values. Villages do indeed raise children. And when the village shares parents’ values, the parents don’t have to do the difficult work of inculcating these values.

But the village — i.e., American society — has radically changed.

Which brings us to the second reason.

Virtually every institution outside the home has been captured by people with left-wing values: specifically the media (television and movies) and the schools (first the universities and now high schools).

In the 1960s and 1970s, American parents were blindsided. Their children came home from college with values that thoroughly opposed those of their parents.

And the parents had no idea how to counteract this. Moreover, even if they did, after just one year at the left-wing seminaries we still call universities, it was often too late. As one of the founders of progressivism in America, Woodrow Wilson, president of Princeton University before becoming president of the United States, said in a speech in 1914, “I have often said that the use of a university is to make young gentlemen as unlike their fathers as possible.” Eighty-eight years later, the president of Dartmouth College, James O. Freedman, echoed Wilson: “The purpose of a college education is to question your father’s values,” he told the graduating seniors of Dartmouth College.

Even now, too few conservative parents realize how radical — and effective — the university agenda is. They are proud that their child has been accepted to whatever college he or she attends, not realizing that, values-wise, they are actually playing Russian roulette — except that only one chamber in the gun is not loaded with a bullet.

And then they come home, often after only year at college, a different person, values-wise, from the one the naive parent so proudly said goodbye.

What to do? I will answer that in a future column. But the first thing to do is to realize what is happening.